You have to do this as a structure. Make the first structure an array of vectors and call it something like ‘Vector Array’. Then make a structure which is an array of Vector Array.
EDIT: You could at the point make a map of vector arrays using an integer, but it would be a lot easier to make an array of vector arrays 
I am trying to store array of vectors in map but i don’t understand how it is possible
suppose if i want to get value of Key 0 - it should give out array of vectors
please let me know if there are any other solutions
There’s nothing to it:
make a structure, the only thing in that structure is an array of vector
make a variable in your BP, which is an array of your new structure
This is about structures:
Make a struct like this:
Only put on thing in it, array of vector.
Can you please expand it